Trace element (Al, Se, Zn, Cu) levels in serum, urine and tissues of burn patients

Burn Patient Metabolism and Nutrition

Following severe burns, patients have unique metabolic derangements that make adequate nutritional support imperative for their survival and recovery. Patients with burns have persistent and prolonged hypermetabolic states that lead to increased catabolism following injury. During rehabilitation, catabolism leads to increased muscle wasting and cachexia. Failure to adequately meet the patient's increased nutritional requirements can lead to poor wound healing, increased infections, and overall organ dysfunction. Because of these risks, adequate assessment and provision of nutritional needs are imperative to care for these patients.

Burns: Classification, Pathophysiology, and Treatment: A Review

Burns and their treatment are a significant medical problem. The loss of the physical barrier function of the skin opens the door to microbial invasion and can lead to infection. The repair process of the damage caused by the burn is impaired due to the enhanced loss of fluids and minerals through the burn wound, the onset of hypermetabolism with the concomitant disruption of nutrient supply, and derangements in the endocrine system. In addition, the initiated inflammatory and free radical processes drive the progression of oxidative stress, the inhibition of which largely depends on an adequate supply of antioxidants and minerals. Clinical experience and research provide more and more data to make the treatment of patients with thermal injury increasingly effective. The publication discusses disorders occurring in patients after thermal injury and the methods used at various stages of treatment.

The Extent of Burn Injury Significantly Affects Serum Micro- and Macroelement Concentrations in Patients on the First Day of Hospitalisation

Burns exceeding 30% of total body surface area (TBSA) result in considerable hypovolemia coupled with the formation and release of inflammatory mediators, leading to subsequent systemic effects known as burn shock. Because of plasma exudation and the associated losses of large quantities of minerals, severe burns can lead to nutritional deficiencies and consequently disrupt homeostasis and metabolism of the entire body. The study group comprised 62 patients, who were divided into 3 groups according to the severity of burns. Serum samples were tested for concentrations of Ca, Mg, Mn, P, K, Zn, Cu, Fe, Se, Na, Cr, Ni, and Al. The mineral concentrations in serum of patients with burn injuries differ significantly from reference values, but this is not affected by the extent of the body burn. There are statistically significant decreases in serum concentrations of elements important for antioxidant protection (Zn, Cu, Se), and significant increases in the concentrations of toxic elements (Al and Ni), which may aggravate the effects associated with the state of burn shock. The Spearman rank correlation analysis did not reveal any statistically significant relationships between the serum concentrations of Mn, Ni, Al, K, Na, P, Mg, Zn, Se, Cr and the affected body surface area and severity of the burn—the values were at the lower end of the reference range. The obtained results indicate that proper nutrition, including elements replenishment, is extremely important in the recovery process of burn patients and time to nutrition is an important factor affecting patient survival after severe burn.

Lower Metal Element Levels in Hypertrophic Scars: A Potential Mechanism of Aberrant Cicatrix Hyperplasia

Background

We investigated levels of the metal elements Ca, Mg, Zn, Fe, and Cu in blood, normal skin (NS), and different types of scar tissue and aimed to elucidate the pathogenesis of hypertrophic scars (HS).

Material/Methods

Tissue specimens were excised from 3 groups of research participants: scar-free, flat scar (FS), and HS groups. Levels of the study elements were measured in blood, NS, and scar tissues with a spectrophotometer. The levels in plasma or in different types of specimens were compared among subgroups. In the FS and HS groups, levels were compared between the scar tissue and NS of each individual. In addition, element differences in exposed and unexposed areas of NS were investigated in the scar-free group. HS fibroblasts (HFB) were cultured in medium with various reduced levels of metal elements to determine the influence of metal elements on fibroblast growth.

Results

Levels of trace elements, including Zn, Fe, and Cu, were significantly lower in HS than in FS. The levels of Ca, Zn, Fe, and Cu were markedly lower in HS than in the patients’ own NS, while the Cu/Zn ratio was higher. However, no such difference was observed in the FS group. No significant difference in element levels was found in either plasma or NS among the 3 groups. Reduced levels of the elements promoted HFB proliferation within 24 h while an inhibition effect was observed at 72 h.

Conclusions

Our findings indicate reduced levels of metal elements in part of the healing microenvironment, suggesting that decreased metal levels may be involved in the pathogenesis of HS.

Vitamin D in burn-injured patients

Recently, many studies have demonstrated pleotropic effects of vitamin D, including immune modulation and cardiovascular system activity. Sufficient vitamin D concentrations and supplementation of vitamin D may be of benefit in burn-injured patients. Low 25(OH)D has been observed in nearly all pediatric and most adult burn patients. Vitamin D has primarily been studied in pediatric burn patients, focusing on bone marker measurements and the incidence of fractures. The preferred vitamin D dose, formulation, and route of administration remain unknown, and there is limited data on the impact of vitamin D status on clinical outcomes. Further research should focus on determining optimal monitoring strategies, supplementation regimens and clinical outcomes like mortality, length of stay and incidence of sepsis.

Nutrition and metabolism in burn patients

Severe burn causes significant metabolic derangements that make nutritional support uniquely important and challenging for burned patients. Burn injury causes a persistent and prolonged hypermetabolic state and increased catabolism that results in increased muscle wasting and cachexia. Metabolic rates of burn patients can surpass twice normal, and failure to fulfill these energy requirements causes impaired wound healing, organ dysfunction, and susceptibility to infection. Adequate assessment and provision of nutritional needs is imperative to care for these patients. There is no consensus regarding the optimal timing, route, amount, and composition of nutritional support for burn patients, but most clinicians advocate for early enteral nutrition with high-carbohydrate formulas.

Nutritional support must be individualized, monitored, and adjusted throughout recovery. Further investigation is needed regarding optimal nutritional support and accurate nutritional endpoints and goals.

Nutrition and metabolism in burn patients

Severe burn causes significant metabolic derangements that make nutritional support uniquely important and challenging for burned patients. Burn injury causes a persistent and prolonged hypermetabolic state and increased catabolism that results in increased muscle wasting and cachexia. Metabolic rates of burn patients can surpass twice normal, and failure to fulfill these energy requirements causes impaired wound healing, organ dysfunction, and susceptibility to infection. Adequate assessment and provision of nutritional needs is imperative to care for these patients. There is no consensus regarding the optimal timing, route, amount, and composition of nutritional support for burn patients, but most clinicians advocate for early enteral nutrition with high-carbohydrate formulas. Nutritional support must be individualized, monitored, and adjusted throughout recovery. Further investigation is needed regarding optimal nutritional support and accurate nutritional endpoints and goals.

Nutrition in burns: Galveston contributions

Aggressive nutrition support is recommended following severe burn injury. Initially, such injury results in a prolonged and persistent hypermetabolic response mediated by a 10- to 20-fold elevation in plasma catecholamines, cortisol, and inflammatory mediators. This response leads to twice-normal metabolic rates, whole-body catabolism, muscle wasting, and severe cachexia. Thus, it is relevant to review the literature on nutrition in burns to adjust/update treatment. Failure to meet the increased substrate requirements may result in impaired wound healing, multiorgan dysfunction, increased susceptibility to infection, and death. Therefore, aggressive nutrition support is essential to ensure adequate burn care, attenuate the hypermetabolic response, optimize wound healing, minimize devastating catabolism, and reduce morbidity and mortality. Here, the authors provide nutrition recommendations gained from prospective trials, retrospective analyses, and expert opinions based on the authors' practices in Galveston, Texas, and Vienna, Austria.

Stressor states and the cation crossroads

Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.

What, how, and how much should patients with burns be fed?

The hypermetabolic response to severe burn injury is characterized by hyperdynamic circulation and profound metabolic, physiologic, catabolic, and immune system derangements. Failure to satisfy overwhelming energy and protein requirements after, and during, severe burn injury results in multiorgan dysfunction, increased susceptibility to infection, and death. Attenuation of the hypermetabolic response by various pharmacologic modalities is emerging as an essential component of the management of patients with severe burn injury. This review focuses on the more recent advances in therapeutic strategies to attenuate the hypermetabolic response and its postburn-associated insulin resistance.

Cation dyshomeostasis and cardiomyocyte necrosis: the Fleckenstein hypothesis revisited

An ongoing loss of cardiomyocytes to apoptotic and necrotic cell death pathways contributes to the progressive nature of heart failure. The pathophysiological origins of necrotic cell loss relate to the neurohormonal activation that accompanies acute and chronic stressor states and which includes effector hormones of the adrenergic nervous system. Fifty years ago, Albrecht Fleckenstein and coworkers hypothesized the hyperadrenergic state, which accompanies such stressors, causes cardiomyocyte necrosis based on catecholamine-initiated excessive intracellular Ca(2+) accumulation (EICA), and mitochondrial Ca(2+) overloading in particular, in which the ensuing dysfunction and structural degeneration of these organelles leads to necrosis. In recent years, two downstream factors have been identified which, together with EICA, constitute a signal-transducer-effector pathway: (i) mitochondria-based induction of oxidative stress, in which the rate of reactive oxygen metabolite generation exceeds their rate of detoxification by endogenous antioxidant defences; and (ii) the opening of the mitochondrial inner membrane permeability transition pore (mPTP) followed by organellar swelling and degeneration. The pathogenesis of stress-related cardiomyopathy syndromes is likely related to this pathway. Other factors which can account for cytotoxicity in stressor states include: hypokalaemia; ionized hypocalcaemia and hypomagnesaemia with resultant elevations in parathyroid hormone serving as a potent mediator of EICA; and hypozincaemia with hyposelenaemia, which compromise antioxidant defences. Herein, we revisit the Fleckenstein hypothesis of EICA in leading to cardiomyocyte necrosis and the central role played by mitochondria.

The selenium status of pediatric patients with burn injuries

BACKGROUND

Dietary selenium (Se) requirements during critical illness are not well known. The objective of this study was to assess the longitudinal Se status of pediatric patients with burns.

METHODS

Twenty patients admitted to our hospital with burns exceeding 10% of their total body surface area were studied longitudinally during the first 8 weeks of admission or until 95% wound closure was achieved. Dietary Se intake was calculated daily, and plasma and urine samples were collected weekly for analyses of plasma Se, urinary Se, and glutathione peroxidase activity.

RESULTS

Patients included in this study were individuals with an average age of 6.5 years ± 5.3 years and with burn injury of a mean total body surface area of 42% ± 21%. Dietary Se intake throughout the study (mean = 60 μg/d ± 39 μg/d) was consistent with established standards for healthy children and did not change throughout the study. Plasma Se (mean = 1.08 μmol/L ± 0.34 μmol/L) and plasma glutathione peroxidase (mean = 3.2 U/g protein ± 1.42 U/g protein) were below reported normal values for healthy American children. Mean urinary Se excretion (65.9 μg/L ± 50 μg/L) exceed dietary Se intake. Plasma Se was inversely related to incidence of total infection (p = 0.04).

CONCLUSIONS

Results from this study indicate that Se status is depressed among pediatric patients with burns and that recommended Se intake for healthy children is likely insufficient for this population. Further studies are necessary to elucidate the amount of dietary Se required to maximize Se stores among pediatric patients with burn injuries.

A dyshomeostasis of electrolytes and trace elements in acute stressor states: impact on the heart

Acute stressor states are associated with a homeostatic activation of the hypothalamic-pituitary-adrenal axis. A hyperadrenergic state follows and leads to a dyshomeostasis of several intra- and extracellular cations, including K, Mg, and Ca. Prolongation of myocardial repolarization and corrected QT interval (QTc) of the ECG are useful biomarkers of hypokalemia and/or hypomagnesemia and should be monitored to address the adequacy of cation replacement. A dyshomeostasis of several trace elements, including Zn and Se, are also found in critically-ill patients to compromise metalloenzyme-based antioxidant defenses. Collectively, dyshomeostasis of these electrolytes and trace elements have deleterious consequences on the myocardium: atrial and ventricular arrhythmias; induction of oxidative stress with reduced antioxidant defenses; and adverse myocardial remodeling, including cardiomyocytes lost to necrosis and replaced by fibrous tissue. To minimize such consequences during hyperadrenergic states, systematic surveillance of electrolytes and trace elements, together with QTc, are warranted. Plasma K and Mg should be maintained at > or =4.0 mEq/L and > or =2.0 mg/dL, respectively (the 4 and 2 rule).

Effect of sub-deficient zinc status on insulin sensitivity after burn injury in rats

Although zinc status is an important parameter in insulin sensitivity, data concerning its implication in noxious burn-induced insulin resistance are scarce. The present study was designed to evaluate the impact of zinc status before burn on the recovery of injury with focus on plasma insulin and glucose levels. The experiment was performed in male adult Wistar rats fed from weaning with a zinc normal diet (80 ppm) or a depleted zinc diet (10 ppm) for 8 weeks and burned to third degree on 20% of their total body surface area. Blood and tissue samples were collected 3, 6, and 24 h after injury in order to study biochemical parameters and the glucose/insulin response in relation with the zinc status. After burn, zinc-depleted rats presented an exacerbated decrease in plasma zinc level. In addition, the burn-induced insulin resistance, leading to protein catabolism, was emphasized, with higher plasma insulin, glucose, and leptin levels in zinc-deficient animals versus normal-fed rats. Our experimental results underlined the interest to early control the zinc status in order to limit the deleterious effects of oxidative stress and insulin resistance in burned patients.

Burn-induced oxidative stress is altered by a low zinc status: kinetic study in burned rats fed a low zinc diet

As an initial subdeficient status of zinc, considered as an essential antioxidant trace element, is frequent in burned patients, we aim to assess the effects of low zinc dietary intakes on burn-induced oxidative stress, in an animal model. After 8 weeks of conditioning diets containing 80 ppm (control group) or 10 ppm of zinc (depleted group), Wistar rats were 20% TBSA burned and sampled 1-10 days after injury. Kinetic evolutions of zinc status, plasma oxidative stress parameters, and antioxidant enzymes were also studied in blood and organs. The zinc-depleted diet induced, before injury, a significant decrease in zinc bone level and the increase of oxidative stress markers without stimulation of antioxidant enzyme activity. After burn, more markedly in zinc depleted animals than in controls, zinc levels decreased in plasma and bone, while increasing in liver. The decrease of thiol groups and GSH/GSSG ratio and the depression of GPx activity in liver are also moderately emphasized. Nevertheless, depleted zinc status could not be considered as determining for oxidative damages after burn injury. Further investigations must also be done to enlighten the mechanism of beneficial effects of zinc supplementation reported in burned patients.

Burns: what are the pharmacological treatment options?

BACKGROUND

Many advances have been made in the understanding and management of burn injury, dramatically increasing pharmacological decision options for burn care professionals. Since burn injury is so multi-faceted, these advances cross many injury processes, both acute and chronic.

OBJECTIVE

The purpose of this review was to highlight the advances and decision options across the entire scope of the burn injury process. The burn-related processes with the most significant pharmacological options of approved products are highlighted.

METHODS

The scope of the current research is the most pertinent literature, which has been summarized with the addition of a personal perspective.

RESULTS/CONCLUSIONS

Many advances over the past decade in multiple fields have made pharmacological options plentiful in burn care. That said, there are many problems for the burn patient which persist, making burn injury still the most severe form of trauma. These issues range from management of a catabolic state with involuntary weight loss in the critical burn to severe itching in the rehabilitating patient. There are also many more treatment options available today. Two key reasons stand out as the most prominent. One reason is the fact that burn care has become much more proactive, by searching out new approaches to solve old problems. Now the treatment approach is altering its focus on manipulating the course of a burn. Examples include the use of temporary skin substitutes in partial thickness or second degree burns, decreasing pain and increasing the healing rate. Another is the use of slow release silver dressing as the topical burn wound antimicrobial of choice, markedly reducing discomfort, the need for dressing changes and an overall decrease in infection. In larger, deeper burns, the approach has changed from the chronic management of an open burn wound to rapid excision and wound closure, eliminating the burn as a source of complications. In addition, there has been a very aggressive approach to controlling the profound hypermetabolic, catabolic response to burns, rather than simply treating the outcome of this predictable post-burn complication. Approaching psychosocial stress again by prevention rather than treatment of established problems is another example. The second reason for increased options and differences in management involves the mindset of those individuals taking care of burns. Tremendous differences in experience are involved in decision-making. Different opinions are based on the expertise and also the personal preferences of those managing the burn.

Inhibition of cyclophoshamide-induced mutagenicity by microsized powder of selenium-enriched green tea in mice

Previously, the antioxidant activity of Se-enriched green tea extracts has been studied in vitro. In the present study, an in vivo micronuclei test was employed to assess the antimutagenic effect of microsized Se-enriched green tea powder (MSTP) in mice bone marrow. Pretreatments of MSTP, micrometer-sized regular tea powder (MRTP), selenite, and MRTP + selenite were given by gavage for 29 consecutive days prior to cyclophoshamide (CP) treatment. Certain key antioxidant enzymes were also investigated to elucidate the mechanism of antimutagenic effect. Results indicated that MSTP and MRTP or selenite alone did not significantly induce micronuclei at either concentration, confirming its nonmutagenicity. In the CP-treated groups, significant suppressions in the micronuclei were recorded following pretreatment with MSTP, MRTP, and selenite administration. The antimutagenic effect of MSTP was evidently observed by significant reduction in the frequencies of micronuclei in bone marrow cells when compared to a positive control group. The administration of MSTP, selenite, and MRTP + selenite also increased the levels of selenium concentration, glutathione peroxidase (GPx), and superoxide dismutase (SOD) enzymes in both blood and liver. However, no pronounced differences in activities of GPx and SOD were found among MSTP, selenite, and MRTP + selenite. The present findings demonstrate that the antimutagenic potential of MSTP could not be solely related to the enhancment of antioxidant enzymes of GPx and SOD.

Alterations of trace elements (Zn, Se, Cu, Fe) and related metalloenzymes in rabbit blood after severe trauma

To investigate the status of the trace elements (TEs) and related metalloenzymes activities in the injury and repair process after severe trauma, we established a rabbit model of severe trauma whose Injury Severity Score (ISS) was 22. Concentrations of blood selenium (Se) and serum copper (Cu), zinc (Zn), iron (Fe), and ferritin were measured on D0 (before injury), and day (D) 1, D2, D3, D6, D9, D14, D21, D28 after trauma, respectively. The activities of glutathione peroxidase (GPx), Cu/Zn superoxide dismutase (Cu/Zn-SOD), myeloperoxidase (MPO), the contents of lipid peroxidation product malondialdehyde (MDA) and serum biochemical profile were detected synchronously. In addition, the morphologic changes of major organs were observed at different time intervals. Results showed that blood Se and serum Zn, Fe contents decreased significantly within 2 weeks after injury. Serum Cu concentration was significantly reduced on D1 but normalized quickly. Serum ferritin level increased during the first week while following an obvious decrease thereafter. The blood GPx activity dropped markedly from D1 to D6, the serum Cu/Zn-SOD activity decreased on D1 and then increased significantly within 2 weeks, and the blood MPO-positive stained cells increased within a week after trauma and followed by a decrease from D14 to D21. The serum MDA increased significantly on D6. Seven of 34 rabbits died in 4-6 days after injury. Biochemistry values and pathological features revealed these rabbits died of multiple organ dysfunction syndrome (MODS). Our experiment suggested that the circulating TEs status is dramatically modified in response to trauma, which might be a factor in MODS.

Kinetic Changes of Oxidative Stress and Selenium Status in Plasma and Tissues following Burn Injury in Selenium-Deficient and Selenium-Supplemented Rats

BACKGROUND

This study investigates the relationship between the burn-induced oxidative stress and the selenium status.

METHODS

The rats were fed with a selenium-adequate diet or a selenium-depleted diet for 5 weeks, before a third-degree thermal injury was applied to the animals. One group of selenium-depleted animals received injections of sodium selenite after the injury. The selenium status and the oxidative stress parameters were measured for 5 days.

RESULTS

The selenium-deficient diet leads to oxidative stress with a high stimulation of the superoxide dismutase activity. After the burn injury, the oxidative stress appears important because the initial selenium status is already impaired and, in all animals, the selenium levels and the antioxidant seleno-dependent glutathione peroxidase (GPx) activity decrease in the plasma and the tissues. A treatment with daily selenium injections is efficient in normalizing selenium levels and restores the GPx activity, but fails to counteract the initial oxidative damages induced by the selenium-deficient diet.

CONCLUSIONS

The selenium status before the burn injury is a modulating factor of the burn-induced oxidative stress. A single selenium supplement is not sufficient to counteract these oxidative damages and henceforth combined antioxidant supplementations should be investigated to improve the early treatment of the burn patients.

Optimization of selenium status by a single intraperitoneal injection of Se in Se-deficient rat: possible application to burned patient treatment

In order to investigate the efficiency of a single selenium (Se) administration in restoring selenium status, Se and antioxidant enzymes were studied in an animal model of Se depletion. In Se-depleted animals receiving or not a single parenteral administration of Se, plasma, red blood cell (RBC), and tissue Se levels were measured concurrently with glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. The oxidative stress was assessed by thiobarbituric acid-reactive species (TBARs), total thiol groups, glutathione, and tocopherol measurements. Our study showed that Se depletion with alterations in the antioxidant defense system (Se and GPx activity decreases) led to an increase of lipid peroxidation, a decrease of the plasma vitamin E level, and SOD activation. Sodium selenite injection resulted after 24 h in an optimal plasma Se level and a reactivation of GPx activity. In liver, brain, and kidney, Se levels in injected animals were higher than those in reference animals. However, this single administration of Se failed to decrease free radical damage induced by Se depletion. Therefore, in burned patients who exhibit an altered Se status despite a daily usually restricted Se supplementation, the early administration of a consistent Se amount to improve the GPx activity should be of great interest in preventing the impairment of the antioxidant status.

Alterations of antioxidant trace elements (Zn, Se, Cu) and related metallo-enzymes in plasma and tissues following burn injury in rats

To improve the nutritional support for burn patients, we evaluated the alterations of selenium, zinc and copper (Se, Zn and Cu) and their possible contributions to an unbalanced antioxidant response to burn injury. These trace elements and the related antioxidant enzymes, glutathione peroxidase (GPx) and superoxide dismutase (SOD), were studied both in plasma (or serum) and tissues of 20% total body surface area (TBSA) burned rats for 10 days. While plasma Se and serum Zn levels significantly decreased 6 h after burn injury, serum Cu levels increased after 1 day and remained elevated the following 9 days. Selenium levels increased in kidney but decreased progressively in liver. The hepatic Zn and Cu concentrations followed a biphasic increase following burn injury. During the first day, GPx activity decreased in plasma and remained unchanged in the organs, except for a moderate diminution in the liver. Liver Cu/Zn SOD activity increased from 6 h to 4 days. In summary, following burn injury, copper and zinc were redistributed to the liver and selenium to the kidney with non-detectable changes in the muscle and brain. Changes in antioxidant enzyme activities following burn injury were significant mainly in the plasma. Early combined antioxidant supplementation to maintain and restore antioxidant status in burn patients requires further study.

An in vivo inducible gene of Pseudomonas aeruginosa encodes an anti-ExsA to suppress the type III secretion system

We have previously reported on the isolation of in vivo inducible genes of Pseudomonas aeruginosa using IVET system. One of such genes isolated from burn mouse infection model encodes a short open reading frame with unknown function. In this study, we demonstrate that this gene product specifically suppresses the expression of type III secretion genes in P. aeruginosa, thus named PtrA (Pseudomonas type III repressor A). A direct interaction between the PtrA and type III transcriptional activator ExsA was demonstrated, suggesting that its repressor function is probably realized through inhibition of the ExsA protein function. Indeed, an elevated expression of the exsA compensates the repressor effect of the PtrA. Interestingly, expression of the ptrA is highly and specifically induced by copper cation. A copper- responsive two-component regulatory system, copR-copS, has also been identified and shown to be essential for the copper resistance in P. aeruginosa as well as the activation of ptrA in response to the copper signal. Elevated expression of the ptrA during the infection of mouse burn wound suggests that P. aeruginosa has evolved tight regulatory systems to shut down energy-expensive type III secretion apparatus in response to specific environmental signals, such as copper stress.

Early evolution of selenium status and oxidative stress parameters in rat models of thermal injury

The objective of the present study was to measure the relationship between selenium status and oxidative stress in two rat models of thermal injury. A non-lethal third-degree burn injury involving 20% (experiment 1) or 40% (experiment 2) of total body surface area (TBSA) was applied to male Wistar rats. Selenium level, glutathione peroxidase (GPx) activity in plasma, red blood cells (RBC) and tissues (liver, kidney, muscle, and brain), and plasma selenoalbumin (Se-alb) were measured in control rats and in burned rats respectively 6 hours after injury and daily from day 1 to day 5. In parallel, lipid and protein oxidative damages, monitored by plasma and tissue thiobarbituric acid reactive species (TBARs) levels and plasma total thiol groups were assessed. We observed a decrease of plasma Se and Se-albumin 6 hours after burn injury. In parallel, plasma GPx activity rapidly decreased and remained significantly lower than in control rats. These alterations were enhanced by the burn injury severity. Plasma TBARs followed the same pattern as that of plasma cholesterol, with an initial decrease and an increase at day 3 in 40% TBSA burned rats. Plasma thiol groups decreased in the two experiments indicating plasma protein oxidation. These results confirm an early oxidative stress in burn injury, and suggest an early selenium mobilization, which might counteract this oxidative stress. These data underline the crucial need of a restored selenium status in burned patients immediately after the burn injury.

Current pharmacotherapy for the treatment of severe burns

The pharmacotherapy of burn care has evolved from the first topical antibiotics instituted > 30 years ago. These have helped greatly to reduce the incidence of burn wound sepsis, but a better understanding of the principles of burn care has resulted in earlier burn wound excision and complete coverage with autograft, cadaver skin, synthetic dressings, and amnion. This has markedly reduced septic complications and ameliorated the hypermetabolic response to burn injury. The hypermetabolic response, which is mediated by hugely increased levels of circulating catecholamines, prostaglandins, glucagon and cortisol, causes profound skeletal muscle catabolism, immune deficiency, peripheral lipolysis, reduced bone mineralisation, reduced linear growth, and increased energy expenditure. Supportive therapy and pharmacological manipulation, acutely and during rehabilitation, with growth hormone, insulin and related proteins, oxandrolone and propranolol can ameliorate the hypermetabolic response, improving survival and long-term outcome. Despite judicious use of topical and systemic antibiotics, opportunistic nosocomial bacterial resistance threatens to annul the improved survival of patients with severe burns. Patterns of emerging resistance encountered in burn units need to be considered, in light of a decreasing antibiotic armamentarium. A holistic approach to pharmacotherapy of severely burned patients including current practice in antimicrobial control, analgesia, sedation, and anxiety management is required. Current therapy of frequently encountered problems, such as post-burn pruritus, prophylaxis of deep venous thrombosis and peptic ulceration, and pharmacological manipulation of inhalation injury in the burned patient is described. Current pharmacotherapy to ameliorate psychosocial problems associated with burns such as acute stress disorder, depression and post traumatic stress disorder are discussed. Better analgesics, newer antibiotics and immune stimulating drugs are required to reduce mortality and morbidity in large burns.

Expression of the soxR gene of Pseudomonas aeruginosa is inducible during infection of burn wounds in mice and is required to cause efficient bacteremia

Burn wounds are prone to infection by Pseudomonas aeruginosa, which is an opportunistic pathogen causing various human diseases. During infection, the bacterium senses environmental changes and regulates the expression of genes appropriate for survival. A purine-auxotrophic mutant of P. aeruginosa was unable to replicate efficiently on burn wounds, suggesting that burn wounds are purine-deficient environments. An in vivo expression technology based on purEK gene expression was applied to the burned mouse infection model to isolate P. aeruginosa genes that are specifically induced during infection. Four such in vivo-inducible (ivi) genetic loci were identified, including the gene for a superoxide response regulator (soxR), the gene for a malate synthase G homologue (glcG), an antisense transcript of a putative regulator responding to copper (copR), and an uncharacterized genetic locus. SoxR of Escherichia coli is known to regulate genes involved in protecting the bacterium against oxidative stress. The expression of soxR was proven to be highly inducible during the infection of burned mice and also inducible by treatment with paraquat, which is a redox-cycling reagent generating intracellular superoxide. The SoxR protein functions as an autorepressor in the absence of paraquat, whereas in the presence of paraquat, this autorepression is diminished. Furthermore, a soxR null mutant was shown to be much more sensitive than wild-type P. aeruginosa to macrophage-mediated killing. In support of this observation, a soxR null mutant exhibited a significant delay in causing systemic infections in the burned mice. Since most mortality in burn patients is caused by systemic infection, the defect in the ability to cause efficient bacteremia in burned mice suggests an important role of the soxR gene in the infection of burn wounds.

The efficacy of trypsin: chymotrypsin preparation in the reduction of oxidative damage during burn injury

This study was mainly aimed to investigate the efficacy of trypsin:chymotrypsin to elicit anti-oxidant properties. In our earlier studies it was observed that the enzyme preparation exhibited an anti-inflammatory action as there was a remarkable reduction in oedema formation and tissue destruction. This led to further study on the amount of lipid peroxidation products formed and the levels of enzymatic and non-enzymatic anti-oxidants and relative trace element contents of copper, selenium, iron and zinc during administration of the enzyme preparation. Decreased formation of lipid peroxidation products was observed in treated group in comparison with the untreated group. Higher levels of enzymatic anti-oxidants mainly super oxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase and non-enzymatic antioxidant namely ceruloplasmin persisted for a longer period of time in the treated group than in the untreated group. No statistical significance was observed in non-enzymatic antioxidants viz. ascorbic acid and tocopherol levels in both the groups. Increased serum copper and selenium levels in the treated group could be related to higher levels of the ceruloplasmin and glutathione peroxidase observed in the treated group. The above studies support the finding that treatment with the enzyme preparation reduced tissue destruction leading to decreased formation of free radicals and subsequent effective scavenging of free radicals by the higher levels of enzymatic and non-enzymatic anti-oxidants.

Assessment of vitamin and trace elementsupplementation in severely burned patients undergoing long-term parenteral and enteral nutrition

The efficacy of an oral supplement of vitamins and trace elements during a longterm artificial parenteral and enteral nutrition was investigated for 3 months in patients with extensive burns. Thirty severely burned patients (22 male, 8 female, age 41 +/- 18 years, range 23-59 years, 33 +/- 12% total body surface area burn, 22% +/- 8 full thickness burn surface area) were included. Every 10 days, from day 10 until day 90, we determined serum levels of: *vitamins B1, B12, A, E, *folic acid, *copper, zinc, iron, *transferrin, albumin, prealbumin, total proteins, *fibronectin, retinol binding protein (RBP), *calcium, *phosphorus, *triglycerides, *total cholesterol, *C reactive protein (CRP), *erythrocyte folic acid. The mean daily nutritional support was 60 Kcals and 0.4 g N per kg of body weight, 70% enterally and 30% parenterally administered, with enteral vitamin and trace element supplementation. On day 10, there was a decrease of the serum level of 19/20 parameters. For 8 parameters (vitamin A, total cholesterol, iron, transferrin, fibronectin, phosphorus, RBP, total proteins), the level was lower than usual. Between day 10 and day 20, a significant normalization of 6 of them was noted, the average levels of transferrin and iron remaining below normal values until day 50. There was a significant decrease in C-reactive protein levels, however above normal limits. No deficiency in vitamins or trace elements was found. Cyclic variations of serum levels occurred which may be more related to volemic, hydroelectrolytic, endocrine and inflammatory disorders than to nutritional problems.